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LMC Down Pressure Help

lacrestadr

New member
Our down pressure works intermiitent on the LMC. It typically works right away and then stops and hour or so into the grooming session, or if it's turned off it won't come back. The up pressure works consistent? Any ideas?

Thanks
 

lacrestadr

New member
We've checked the wiring and have since replaced the filter. It hasn't been used since the filter change. We'll see if that does it. If it is the filiter wouldn't it also affect the up pressure?

Thanks for your replies!!
 

snow dog

New member
the filter is easy, most guys change them on a regular basis. i would be looking at the hydrallic valve that operates the down pressure.
 

MNoutdoors RIP

Gone But Not Forgotten
GOLD Site Supporter
Our down pressure works intermiitent on the LMC. It typically works right away and then stops and hour or so into the grooming session, or if it's turned off it won't come back. The up pressure works consistent? Any ideas?

Thanks

Make sure all of the hydraulic couplers are screwed on all the way even just a little bit loose and they will act like that. we have run into that several times on other LMC units .
 

snow dog

New member
Other than a new filter, what have yoou done to correct the problem? How about posting some pictures of the machine detailing the problem areas
 

Dr. Zaugg

New member
I would bet that the coil is getting weak.or is shorted out. It can pull the valve when it is cold, but when it is activated it gets hot and it will not pull the valve again. Switch the coils on the valve and see if the problem goes to the other side. I have complete valves, the coils and the whole valve block. I bet on the coil though.
Paul
 

snow dog

New member
I would bet that the coil is getting weak.or is shorted out. It can pull the valve when it is cold, but when it is activated it gets hot and it will not pull the valve again. Switch the coils on the valve and see if the problem goes to the other side. I have complete valves, the coils and the whole valve block. I bet on the coil though.
Paul


Paul,

Is it an electric solinoid similar to a pisten bully?
 

Dr. Zaugg

New member
ummm, yes and no. Pb used several types. I think you have either a "C" cat or "CF". Either way the up/down valve is in the right rear side of the tub. It is about six inches square and about three inches thick. It will have two kiinda round coils showing with two wires to each. Depending on the version, there are different looking coils and valves. You can start the cat, lower the tiller(do not start the tiller) engage the down pressure, and hold a wrench up to each of the coils. The "hot" one will draw the wrench. Then, switch to up pressure and see if the other coil holds the wrench tighter. If so,(it will be obvious) the coil is either weak or just shot. If you want to use down more than up, then just switch the coils for a while or e-mail me a picture of them and i can send you a new one. Be sure to check, and clean the ground connections too!!
paul
 

lacrestadr

New member
First let me thank all of you for the great troubleshooting ideas. We've swithced the coils to see if that was the cause. The problem continues. The coil had the magnetic response noted and there was still no down pressure....The coil that was the down pressure works fine as the up pressure. Of course we rarely use the up pressure. It may stop working also, we just don't use it enough to know..
 

Dr. Zaugg

New member
SOOO, the plot thickens! unscrew both of the valves that the coils are on and switch them, I bet the problem will go to the up pressure side. those valves constantly went bad. While it is out photograph it and record the numbers on it and i can send you a replacement.
Paul
 

lacrestadr

New member
Paul, I think it may be working, maybe the filter did it? We've been dealing with 4 feet of fresh snow over the last couple of days and only used it a bit. I will have more time tonight to test it and let you know. Thanks again for all the help, it's really appreciated:clap:
 

lacrestadr

New member
The down pressure isn't working...Seems to start strong and fade by the end of the grooming session. Paul can yo give me a little more detail in regard to switching out the valves. Ihave no clue what they look like..
Thanks
 

Dick

Member
check the hose for that function I have had the hose collapse on the inside and cause that problem Good Luck
 

Dr. Zaugg

New member
Look under the rear lid. At the right hand side just under the lid is a square hydraulic valve block. It has a bunch of hoses going to it. It also has two electric coils on the front side. Just remove the retaining nuts and pull the coils off, and you will have the valves exposed. If memory serves me, use a 1" wrench and remove both valves(unscrew them) and switch positions. Switch the coils too. New question, does the blade wing functions also slow down when you have lost down pressure?? It is related!
Paul
 

lacrestadr

New member
We have an 1800, no wings (we have those on the 3700).....the valve block is on the right side. We'll give it a shot and get back to you.

Do you have a heater switch (2 speed pull knob) for the LMC 1800?

Thanks
 

Dr. Zaugg

New member
Does your 3700 have a Cat engine? as i assume it does? There were a very few of the last AC-3700s that had a up/down pressure system installed. About the 1800, i don't have any parts except for maybe some track cleats.
Paul
 

lacrestadr

New member
Switched valves and we end up with the same problem, up pressure ok, down pressure good for about 2-3 hours then it quits....Any other suggestions??? Would replaceing the 0 rings on the valves make a difference?? Could it be the down pressure side within the pump and could we swith up pressure line with down to test??
Thanks!
 

Dr. Zaugg

New member
Ok, so did you also keep the electric coils with the valves? What is the gauge reading when the down pressure is cold and when it is hot and not. It should be no more than 340PSI. If it is set much higher, then the excess flow is heating the relief valve and causing the issue. it cannot handle any more pressure than 340.
 

lacrestadr

New member
Lift cylinder soesn't show any signs of leaking.
Yes we kept the coils with the valves, I had previously switched them to check them..We'll check the pressure...
Thanks to all for the ideas!
 

Thiokol2track

Bronze Member
SUPER Site Supporter
I had a problem recently that the oil was getting hot and noticed that there was ice on the hydraulic oil cooler in front of the radiator. In the manual it shows a thermostat in an aluminum "housing" or valve . This is to warm the oil quicker in cold weather then send it to the cooler when it reaches 120 degrees. Says in the manual,you should have a rebuild kit handy! So the thermostats are known to stick. What was happening was the oil was not getting cooled and just making a short loop back to the tank, and building more heat. Rebuild kit was $45 and a new valve was $80 so i just replaced the valve. Is it possible your oil is heating up after 2-3hrs of grooming??

The thermostatic valve was located behind the last pump, not far from the hydraulic filter. Hope this helps!
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
Lift cylinder soesn't show any signs of leaking.
Yes we kept the coils with the valves, I had previously switched them to check them..We'll check the pressure...
Thanks to all for the ideas!
the leak is internal if you have power up and power down you have a double acting ram when the oil is cool it stays in the proper chamber when it is warm it bypasses the piston into the other chamber releaving the pressure for your power down and allowing the blade to float up you will see no leak around the chrome ramthe only way to check this would be to remove the up line after down pressure is applied and see if oil comes oozing out that port on the ram the pump does nothing but apply pressure once applied the valve holds the pressure till you make a change
 
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